On Dec. 2, 1859, militant abolitionist John Brown was hanged for his raid on Harpers Ferry the previous October. Artist Georges-Pierre Seurat was born in Paris.

On this date: In 1804, Napoleon crowned himself Emperor of the French.

In 1823, President James Monroe outlined his doctrine opposing European expansion in the Western Hemisphere.

In 1927, Ford Motor Co. formally unveiled its second Model A automobile, the successor to its Model T.

In 1939, New York Municipal Airport-LaGuardia Field (later LaGuardia Airport) went into operation as an airliner from Chicago landed at one minute past midnight.

In 1942, an artificially created, self-sustaining nuclear chain reaction was demonstrated for the first time, at the University of Chicago.

In 1954, the Senate voted to condemn Wisconsin Republican Joseph R. McCarthy for conduct that "tends to bring the Senate into disrepute."

In 1961, Cuban leader Fidel Castro declared himself a Marxist-Leninist who would eventually lead Cuba to Communism.

In 1969, the Boeing 747 jumbo jet got its first public preview as 191 people, most of them reporters and photographers, flew from Seattle to New York City.

In 1970, the Environmental Protection Agency began operating under director William Ruckelshaus.

In 1980, four American churchwomen were raped and murdered outside San Salvador. (Five national guardsmen were convicted in the killings.)

In 2001, in one of the largest corporate bankruptcies in U.S. history, Enron filed for Chapter 11 protection.

Ten years ago: The Supreme Court ruled unanimously that after knocking, police don't have to wait longer than 20 seconds before breaking into the home of a drug suspect. Authorities in Ohio announced that they had linked 12 shootings along a 5-mile stretch of interstate around Columbus, including one that killed a woman and another that broke a window at an elementary school. (A suspect, Charles A. McCoy Jr., later pleaded guilty to manslaughter and 10 other charges, and was sentenced to 27 years in prison.)

Five years ago: President-elect Barack Obama promised swift action on an economic plan "to solve this crisis and to ease the burden on our states." Republican Saxby Chambliss won a Georgia runoff, denying Democrats a 60-seat, filibuster-proof majority in the Senate (until Al Franken's belated victory over Norm Coleman in Minnesota). Folk singer Odetta died in New York at age 77. Henry Molaison, the patient known as "H.M." whose severe amnesia led to groundbreaking studies of how memory works, died in Connecticut at age 82.

One year ago: In the aftermath of a murder-suicide involving Kansas City Chiefs linebacker Jovan Belcher, NBC's Bob Costas delivered a "Sunday Night Football" halftime commentary supporting gun control. Israel Keyes, charged in the death of an Alaska barista, was found dead in his jail cell in Anchorage in an apparent suicide; authorities announced that he'd been linked to seven other possible slayings in three other states. Hundreds of concrete slabs, each weighing more than a ton, fell from the roof of a highway tunnel west of Tokyo, crushing vehicles below and killing nine people.